I just spent some time and made it. not sure if you have already figured it out or not.

After you deployed your Ruby web app (Rails, Sinatra, ...) to heroku, you should setup another heroku apps for Faye. Either you use the same Ruby web app source code or use Faye-Heroku-Cedar.
to start the Faye correctly on heroku, the key point is about the Procfile.

what Procfil does in this case is just running the "rakeup -R private_pub.ru" command to start the service.